Electrically conductive, elastically stretchable hybrid yarn, method for manufacture thereof and textile product with a hybrid yarn of this kind

ABSTRACT

The invention relates to an electrically conductive, elastically stretchable hybrid yarn ( 3 ), in which an elastically stretchable core filament ( 1 ) is surrounded by an electrically conductive fibre sheath ( 2 ). This results in improved technical properties of a hybrid yarn of this kind in conjunction with a simplified manufacturing method.

FIELD OF THE INVENTION

The present invention relates to the field of textile yarns and the products in which yarns of this kind are used, in particular in the case of yams that are electrically conductive and elastically stretchable. Products of this kind are, for example, sheet-type heating elements such as those used for seat heating in the automotive field. Yams of this type are also used with floor coverings, blankets, heatable clothing or portions thereof and similar, and also shielding textiles to divert electric fields.

Textile electrical surfaces are used to adjust the temperature of environments that are in contact with the human body. In this regard, they are generally joined to other textile layers by stitching or gluing. In other cases, suitable heating conductors form surfaces comprising heating conductors and their supply lines. In this regard, the shape and size are adapted to match the applicable conditions of use.

PRIOR ART

Although metallic wires are very suitable for conducting current, they themselves possess few textile properties and this is a drawback when processing, such as weaving, knitting, etc. These wires are in this regard completely inelastic and do not have a textile handle. To improve this situation, a metallic wire is combined with a textile yam or filament, generally by winding or twisting. The combination comprising wire and elastic thread achieves a certain flexibility due to the elasticity of the textile filament The two elements already exist as individual filaments before the winding process and have to be manufactured in individual separate preliminary processes and are brought together by the winding process. However, in this regard the metallic handle and the rigidity can only be influenced to a limited extent

Known from WO 2004/097089 A1 is an electrically conductive, elastic composite yarn comprising an elastic element. This elastic element comprises one or more elastic filaments and is covered by at least one, but preferably a plurality of conductive filaments (longitudinal filaments). Each conductive thread surrounding the elastic element has a length that is greater than the drafted length of the elastic element so that all of the elongating stress imposed on the composite yarn is carried by the elastic element. This publication cites U.S. Pat. No. BS 6,341,504. This mentions an elastic textile product which has a conductive wire for use in garments. This is intended for indicating physiological body functions. This publication describes an elongated band of elastic material which is stretchable in the longitudinal direction and comprises at least one conductive wire either lying on or provided inside the elastic band.

DE 103 42 787 A1 discloses an electrically conductive yarn comprising at least one elastic core filament, at least one electrically conductive filament wound around the core filament and at least one non-conductive filament wound around the core filament which limits the stretch of the whole electrically conductive yarn. A similar composite yarn is disclosed in DE 102 42 785 A1 and WO 2004/027132 A1.

PRESENTATION OF THE INVENTION

A technical problem (object) of the invention is to provide an electrically conductive, elastically stretchable hybrid yam which is simple to manufacture and more effective with respect to electric conductivity and elastic stretch than the composite yams known to date.

This object is achieved according to the invention by an electrically conductive, elastically stretchable hybrid yarn with an elastically stretchable core and an electrically conductive element assigned to the core on the circumferential side which permits the elastic stretch of the core, whereby the electrically conductive element comprises a fibre sheath surrounding the core at least partially and at least partially comprising electrically conductive fibres which are bonded with each other.

This produces a homogeneous yarn with a high degree of elasticity with the total elasticity extensively corresponding to the elasticity of the elastic core filament.

Preferably, the core comprises at least one filament which is surrounded by the fibre sheath. In this regard, the at least one filament may comprise textured polyester or Lycra or a similar material. There can also be at least one inelastic core filament which is laid in such a way as to permit a desired stretch of the elastic core filament but in addition also limits the stretching.

Particularly good conductivity with the use of fibres is obtained in particular if the electrically conductive fibres are selected from the group:

-   -   conductive polyester fibres; high-grade steel fibres; carbon         fibres; metal-coated polymers, silver-plated, copper-plated;         nickel-plated carbon fibres and similar.

A possible yarn number range is 2000-40 tex (Nm 0.5-25), whereby the fibres can have a fineness of 1.0-3.3 dtex and the fibres can have a cut length of 35-60 mm.

Conductive fibres such as carbon fibres, nickel-coated carbon fibres, metal fibres and fibres made of metal-coated polymers have no rigidity as individual fibres and, due to the fine titre, have extensively textile handle features.

To improve the bond between the elastic core filament and conductive sheath fibres, during the mixing process, fusible fibres can be mixed into slubbings or drawing slivers produced in a conventional preliminary spinning stage, preferably in an amount of 5-10%. Thermal after-treatment of the elastic, conductive yam, which can, for example, be combined with a rewinding process or even take place at the same time as the subsequent textile finishing of the finished fabric, causes the fusible fibres to adopt a plastic state and after cooling bond the core filament and sheath fibres which can considerably improve the antislip properties of the hybrid yam without noticeably reducing the electrical conductivity.

The hybrid filament is preferably produced using the so-called friction spinning method with which the fibres can be bonded with the core. This friction spinning method was developed by the company Dr Fehrer Linz AG, the Dref2/Dref2000 System, which is familiar to a person skilled in the art.

The object is also achieved by a method for manufacturing a hybrid yam by:

-   -   the introduction of a core filament, which can also comprise         single filaments     -   the breaking down of slubbings or a drawing sliver into         electrically conductive individual fibres and optionally fusible         fibres in a spinning process     -   laying the fibres substantially at right angles around the         continuous core filament, and     -   friction-bonding the fibres with the core filament using the         so-called friction spinning method.

If fusible fibres are present, the heating can take place as thermal after-treatment of the elastic, conductive hybrid yam, which can, for example, be combined with a rewinding process, or even during the subsequent textile finishing of the finished fabric. During this, the fusible fibres adopt a plastic state and after cooling bond the core filament and sheath fibres, which considerably improves the antislip properties of the hybrid yarn without noticeably reducing the electrical conductivity.

The object is also achieved by a textile product containing the aforementioned hybrid yarn.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective, schematic view of an electrically conductive, elastically stretchable hybrid yarn.

FIG. 2 is a perspective view of a device for the friction spinning method.

DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

FIG. 1 is a perspective view of a part of a hybrid yarn 3 in which a portion of the hybrid yarn in perspective view only shows the core filament 1, which here comprises a plurality of single filaments 4 which are bundled into a total core filament. This is not absolutely necessary, the core filament can also be embodied as a single filament. This core filament is surrounded by a fibre sheath 2 comprising a plurality of short individual fibres 5.

The core filament 1 is an elastically stretchable filament which can, for example, comprise textured polyester or Lycra which is spun with conductive fibres. The total yarn has, for example, a yarn count range of 2000-40 tex (Nm 0.5-25). The fibre sheath is, for example, made of fibres with a fineness of 1.0-3.3 dtex and a cut length of 35-60 mm. To form the sheath, the fibres form a bond but this does not impair the elastic stretch of the core filament. This is even more applicable if, in a mixing process, fusible fibres are mixed into the sheath fibres, which are electrically conductive, for example in an amount of 5-10%. This serves to improve the bond between the elastic core filament and the conductive sheath fibres. These fusible fibres are, for example, mixed into the slubbings or drawing slivers produced in a normal preliminary spinning stage.

The sheath fibres can be conductive polyester fibres, high-grade steel fibres or metal and preferably silver or copper-coated polymers plus carbon fibres or nickel-plated carbon fibres.

The invention is based on the idea of spinning an elastic, textile filament such as, for example, textured polyester or Lycra with conductive fibres. In this regard, the elastic filament forms the heart or the core of the yarn and the conductive fibres, not as yet a finished filament, are themselves bonded with the core filament by means of a special spinning process. This is performed with a device such as that shown in FIG. 2. In this device, the reference number 6 indicates the slubbings introduced, which are broken down into individual fibres by means of an opening cylinder 7. Reference number 8 designates a guide roll for introducing the core filament and reference number 9 a drawing-off disc for removing the finished yam in the region of a rinsing unit 10 with a dirt extractor 11 provided on its side.

The hybrid yarn 3 shown in FIG. 1 is manufactured with a device of this kind. It is possible to use the so-called friction spinning method developed by the company Dr Fehrer Linz AG, the Dref2/Dref2000 System, which is known to every person skilled in the art.

During the spinning process, the slubbings are broken down into individual fibres and laid at right angles around the continuous core filament and friction-bonded therewith. This produces a homogeneous yarn with a high degree of elasticity, which in overall elasticity extensively corresponds to the elasticity of the elastic core filament.

The conductive fibres, such as carbon fibres, nickel-coated carbon fibres, metal fibres or fibres made of metal with coated polymers have no rigidity as individual fibres and, due to their fine titre, have extensively textile handle features. To improve the bond between the elastic core filament and conductive sheath fibres, during the mixing process, fusible fibres may be mixed into the slubbings or drawing slivers, which are produced in a conventional preliminary stage, in an amount of 5-10%. Thermal after-treatment of the elastic, conductive yarn, which can, for example, be combined with a rewinding process or even takes place at the same time as the subsequent textile finishing of the finished fabric, causes the fusible fibres to adopt a plastic state and, after cooling, bond the core filament and sheath fibres, which improves the antislip properties of the hybrid yarn without noticeably reducing the electrical conductivity. 

1. Electrically conductive, elastically stretchable hybrid yam with an elastically stretchable core (1) and an electrically conductive element assigned to the core (1) on the circumferential side which permits the elastic stretch of the core, characterised in that the electrically conductive element comprises a fibre sheath (2) surrounding the core (1) at least partially and at least partially comprising electrically conductive fibres (5) which are bonded with each other.
 2. Hybrid yam according to claim 1, characterised in that the core is formed from at least one filament (4) surrounded by the fibre sheath (2).
 3. Hybrid yam according to claim 2, characterised in that the at least one filament (4) comprises textured polyester or Lycra or a similar material.
 4. Hybrid yam according to claim 1, characterised in that the electrically conductive fibres (5) are selected from the group: conductive polyester fibres; high-grade steel fibres; carbon fibres; metal-coated polymers, silver-plated, copper-plated; nickel-plated carbon fibres and similar.
 5. Hybrid yam according to any one of claims 1 to 4, characterised in that the fibres (5) have a fineness of 1.0-3.3 dtex.
 6. Hybrid yam, according to any one of claims 1 to 5, characterised in that the fibres (5) have a cut length of 35-60 mm.
 7. Hybrid yarn according to claim 1, characterised in that fusible fibres are mixed into the electrically conductive fibres (5).
 8. Hybrid yam according to claim 7, characterised in that 5-10% fusible fibres are mixed in.
 9. Hybrid yam according to any one of claims 1 to 8, characterised in that the fibres are bonded with the core by means of the so-called friction spining method.
 10. Method for manufacturing a hybrid yam according to any one of claims 1 to 9, characterised by the introduction of a core filament, which can also comprise single filaments the breaking down of slubbings or a drawing sliver into electrically conductive individual fibres and optionally fusible fibres in a spinning process laying the fibres substantially at right angles around the continuous core filament, and friction-bonding the fibres with the core filament using the so-called friction spinning method.
 11. Method according to claim 10, characterised in that if fusible fibres are present, they are heated.
 12. Textile product containing a hybrid yam according to any one of claims 1 to
 9. 